diff --git a/SketchWidget.py b/SketchWidget.py
index 3f1f41a..5499f3c 100644
--- a/SketchWidget.py
+++ b/SketchWidget.py
@@ -64,6 +64,7 @@ class SketchWidget:
 
         glViewport(0, 0, width, height)
         glMatrixMode(GL_PROJECTION)
+        glLoadIdentity()
         glOrtho(0, width, 0, height, 1.0, -1.0)
 
         glMatrixMode(GL_MODELVIEW)